startRenderMonitoring

Starts owner-thread monitoring at an operation boundary with existing nodes as the baseline. A second active monitor, reentrant access, or an unavailable tree is rejected without changing the screen. The caller closes the monitor; terminal tree cleanup also releases it automatically.

Starts monitoring with an explicit bounded node-record capacity for large test fixtures. Capacity must be in 1..65,536 and applies to live plus retired identities in one checkpoint interval. Adapters without this capability retain their existing 4,096-record entry point and reject other capacities.